Method and system for determining placement of a tracheal tube in a subject

ABSTRACT

According to various embodiments, a tracheal tube may employ optical sensing techniques for determining a distance between the inserted tube and an anatomical structure, such as a carina. The distance information may provide an indication as to whether or not the tracheal tube is properly placed within the trachea. The optical techniques may include backscattered intensity measurements.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 12/420,176now U.S. Pat. No. 8,280,489, filed Apr. 8, 2009, entitled “Method andSystem for Determining Placement of a Tracheal Tube in a Subject” in thename of Youzhi Li et al., and assigned to Nellcor Puritan Bennett LLC,which is incorporated by reference herein in its entirety.

BACKGROUND

The present disclosure relates generally to medical devices and, moreparticularly, to airway devices, such as tracheal tubes.

This section is intended to introduce the reader to aspects of the artthat may be related to various aspects of the present disclosure, whichare described and/or claimed below. This discussion is believed to behelpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

In the course of treating a patient, a tube or other medical device maybe used to control the flow of air, food, fluids, or other substancesinto the patient. For example, tracheal tubes may be used to control theflow of air or other gases through a patient's trachea. Such trachealtubes may include endotracheal (ET) tubes, tracheotomy tubes, ortranstracheal tubes. In many instances, it is desirable to provide aseal between the outside of the tube or device and the interior of thepassage in which the tube or device is inserted. In this way, substancescan only flow through the passage via the tube or other medical device,allowing a medical practitioner to maintain control over the type andamount of substances flowing into and out of the patient.

For example, a patient may be intubated when an endotracheal tube isinserted through the patient's mouth and into the trachea. Often, suchintubation procedures may be performed during medical emergencies orduring critical care situations. As such, healthcare providers maybalance a desire for speed of intubation with a desire for accurateplacement of the tube within the trachea. However, proper placement of atracheal tube may be complex. In certain situations, placement may beaided with visualization of the trachea performed during laryngoscopy.During an intubation procedure, a practitioner may employ a lightedlaryngoscope during introduction of the endotracheal tube. However,often the visualization of the trachea is poor because of patientsecretions that may obscure the laryngoscope. In addition, suchvisualization during introduction of the tube may not account forongoing changes in the tube's position within the trachea that may occurwhen a patient coughs, which may dislodge a tube from its desiredlocation, or when a patient is jostled or moved within a care setting,which may change the position or angle of the tube within the trachea.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the disclosure may become apparent upon reading thefollowing detailed description and upon reference to the drawings inwhich:

FIG. 1 illustrates an exemplary system including an endotracheal tubewith a coherent light source and detector according to embodiments;

FIG. 2A is a schematic diagram of optical sensing components including abeam splitter that may be coupled to a tracheal tube according toembodiments;

FIG. 2B is a schematic diagram of an alternative arrangement of opticalsensing components including a beam splitter that may be coupled to atracheal tube according to embodiments;

FIG. 2C is a schematic diagram of optical sensing components includingan optical coupler that may be coupled to a tracheal tube according toembodiments;

FIG. 2D is a schematic diagram of optical sensing components including amulti-port circulator that may be coupled to a tracheal tube accordingto embodiments;

FIG. 3 is a flow diagram of a method of operating a tracheal tubeaccording to embodiments;

FIG. 4 is a perspective view of an exemplary endotracheal tube of FIG.3; and

FIG. 5 is a perspective view of an exemplary distal tip of a trachealtube with embedded optical fibers for that may be coupled to a lightsource and photodetector.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present disclosure will bedescribed below. In an effort to provide a concise description of theseembodiments, not all features of an actual implementation are describedin the specification. It should be appreciated that in the developmentof any such actual implementation, as in any engineering or designproject, numerous implementation-specific decisions must be made toachieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

A tracheal tube may be used to seal a patient's airway and providepositive pressure to the lungs when properly inserted into a patient'strachea. Positioning the tracheal tube at a desired position within thetrachea, for example during endotracheal intubation, may improve theperformance of the tracheal tube and reduce clinical complications. Inparticular, the distal inserted end of the endotracheal tube may bepositioned in the patient's trachea at a location substantially betweenthe patient's vocal cords and carina. If the tube cuff is not insertedfar enough past the vocal cords, for example, the tube may become moreeasily dislodged. If the tube is inserted too far into the trachea, suchas past the carina, then the tube may only function to adequatelyventilate one of the lungs, rather than both. Thus, proper placement ofthe distal tip of the tube may result in improved ventilation to thepatient.

Provided herein are tracheal tubes and systems for facilitating properplacement of the tracheal tube relative to certain anatomical structuresin and around the patient's airway and trachea. Such tracheal tubes mayinclude assemblies for shining light into the trachea and detecting thereturned light. The intensity of the detected light may be affected byits interaction with an anatomical structure. Accordingly, informationrelated to the intensity of the detected light may be used to determinea distance from the tube to the anatomical structure in question. Incertain embodiments, a distance from the distal end of the tracheal tubeto the carina may be determined. A healthcare provider may then use theinformation about the location of the tracheal tube relative to thecarina to determine whether the tube is properly placed or whether theposition of the tube should be adjusted.

In certain embodiments, the disclosed tracheal tubes, systems, andmethods may be used in conjunction with any appropriate medical device,including without limitation a feeding tube, an endotracheal tube, atracheotomy tube, a circuit, an airway accessory, a connector, anadapter, a filter, a humidifier, a nebulizer, nasal cannula, or asupraglottic mask/tube. The present techniques may also be used tomonitor any patient benefiting from mechanical ventilation, e.g.,positive pressure ventilation. Further, the devices and techniquesprovided herein may be used to monitor a human patient, such as a traumavictim, an intubated patient, a patient with a tracheotomy, ananesthetized patient, a cardiac arrest victim, a patient suffering fromairway obstruction, or a patient suffering from respiratory failure.

FIG. 1 shows an exemplary tracheal tube system 10 that has been insertedinto a patient's trachea. The system 10 includes a tracheal tube 12,shown here as endotracheal tube, with an inflatable balloon cuff 14 thatmay be inflated to form a seal against tracheal walls 16. The trachealtube 12 may also include one or more optical fibers 18 that areassociated with the tube 12. The optical source fiber 18 may beconfigured to pass light from a source 24 through a distal end 27 of theendotracheal tube and into a patient's trachea such that a portion ofthe emitted light may interact with a carina 28. The emitted light maybe transferred back through the optical fiber 18, which may be coupledto a light detector 26.

The system 10 may also include devices that facilitate positive pressureventilation of a patient, such as a ventilator 22, which may include anyventilator, such as those available from Nellcor Puritan Bennett LLC.The system may also include a monitor 30 that may be configured toimplement embodiments of the present disclosure. The monitor 30 may be astand-alone device or may be coupled to another patient monitor or tothe ventilator 22. The monitor 30 may include a microprocessor 32coupled to an internal bus 34 and a display 36.

The monitor 30 may include certain elements for controlling the lightsource 24 and the light detector 26. The monitor 30 may drive light fromsource 24, which in turn may be carried by optical fiber 18. The lightmay pass into the tissue, where it may be variously scattered, absorbed,and/or reflected and then detected by detector 26. A time processingunit (TPU) 38 may provide timing control signals to light drivecircuitry 40, which controls when the light source 24 is activated, andif multiple light sources 24 are used, the multiplexed timing for thedifferent light sources. TPU 38 may also control the gating-in ofsignals from detector 26.

In an embodiment, the monitor 30 may be configured to receive signalsfrom the detector 26 and store the signals in a mass storage device 42,such as a RAM, ROM, optical storage device, flash memory device,hardware storage device, magnetic storage device, or any other suitabledevice permitting memory storage. The signals may be accessed andoperated according to microprocessor 32 instructions. In certainembodiments, the signals may be related to a placement of the trachealtube 12 within the patient's trachea and may be processed by the monitor30 to indicate whether the tracheal tube 12 is properly placed. Themonitor 30 may be configured to provide an indication about theplacement of the tracheal tube 12 within the patient's trachea, such asan audio alarm, visual alarm or a display message if the tracheal tube12 is too far or too close to certain anatomical structures, such as thecarina 28, or outside of a predetermined placement range. In anembodiment, based at least in part upon the received signalscorresponding to the light received through optical fiber 18,microprocessor 32 may calculate a placement parameter of theendotracheal tube 12 using various algorithms. In an embodiment, theplacement parameter may relate to a distance, d, 44 between the distalend 27 of the tube 12 and the carina 28 or other anatomical structure.

FIGS. 2A-D are schematic representations of optical sensor arrangementsthat may be incorporated into system 10 for analyzing placement of atracheal tube 12 within a patient's trachea. From the change inintensity of the returned light beam 48 after its interaction with thecarina 28 or any other anatomical feature of interest, the distance, d,44 to the carina 28 may be estimated, as discussed in more detail below.In embodiments, such arrangements may involve measuring the intensity ofthe emitted light 46 to generate a reference intensity measurement towhich changes in the intensity of the returned light beam 48 may becompared. A calculated return distance, R, 45 may be equal to thedistance 44, d (i.e., the distance between the distal end 27 and thecarina 28).

It should be understood that the depicted embodiments are exemplary, andthe relationships between the optical components may vary. Inparticular, in embodiments in which optical fibers 18 are employed, thespatial relationships between light source 24, detector(s) 26, and beamsplitter 50 (or optical coupler or multi-port circulator) may bealtered. FIG. 2A depicts an embodiment in which one optical fiber 18 ais dedicated to transmit light 46 and a second optical fiber 18 b isdedicated to collect the returned light 48. In embodiments, opticalfibers 18 a and 18 b may be part of a single fiber bundle. As shown, theemitted light 46 is split at beam splitter 50 so that a portion of thelight, light beam 46 a, is directed towards a detector 26 a, which maythen generate a reference signal related to the intensity of the emittedlight 46. The light beam 46 may pass through the airway until the lightinteracts with an anatomical tissue structure, such as a carina 28. Thereturned light beam 48 may be collected optical fiber 18 b and detectedby light detector 26 to generate light intensity signals that may beanalyzed by monitor 30.

In one implementation, a single fiber 18 may be used to emit light andreturn the light that is reflected/scattered by an anatomical structure.In FIG. 2B, a light beam 46 from source 24 may be emitted and split atbeam splitter 50 so that a portion of the light, light beam 46 a, isdirected towards a detector 26 a, which may then generate a referencesignal related to the intensity of the emitted light. The rest of thelight beam 46 may be emitted from the distal end 27 of tube 12. Asnoted, light from source 24 may be transmitted through optical fiber 18and the returned light beam 48 may pass through the same fiber 18. In analternative embodiment, shown in FIG. 2C, instead of a beam splitter 50,a 2×2 optical coupler 54 may be used to split off a portion of light,light beam 46 a, to impinge a detector 26 a and generate a referenceintensity signal. FIG. 2D depicts an embodiment in which a multi-portcirculator 56 may allow an arrangement in which a single detector may beused to detect the return beam 48.

The signal generated at one or more detectors 26 may be communicated tothe monitor 30. The incoming signals may include an emitted lightintensity signal from the detector 26, which may be a measure of theintensity of the emitted light beam 46. The incoming signals may alsoinclude an intensity signal of the returned light beam 48. The monitor30 may control the light source 24 and light detector 26. The TPU 38 maycontrol the gating of signals from one or more light detectors 26 inconjunction with the light drive circuitry 40. In embodiments, themonitor 30 may control a switch from emitting light to detecting lightwithin the optical fiber 18.

In embodiments, the intensity of the emitted light beam 46 may beestimated or determined without splitting a portion. For example, lightsource 24 may be factory calibrated such that the intensity is known.The intensity value may be stored as a calibration factor by the monitor30 or by a separate encoder associated with the light source 24 that maybe accessed and read by the monitor 30.

The light source 24 and a detector 26 may be of any suitable type. Forexample, the light source 24 may be one or more light emitting diodesadapted to transmit one or more wavelengths of light, for example in thered to infrared range, and the detector 26 may be one or morephotodetectors (e.g., photodiodes) selected to receive light in therange or ranges emitted from the light source 24. A light source 24 maybe a coherent light source, such as a laser diode or a vertical cavitysurface emitting laser (VCSEL). The light source 24 may include abroadband or “white light” source, in which case the detector couldinclude any of a variety of elements for selecting specific wavelengths,such as reflective or refractive elements or interferometers. It shouldbe understood that, as used herein, the term “light” may refer to one ormore of, millimeter wave, infrared, visible, ultraviolet, gamma ray orX-ray electromagnetic radiation, and may also include any wavelengthwithin the infrared, visible, ultraviolet, or X-ray spectra.

In embodiments, the light source 24 and detector 26 may be directlycoupled to the distal end 27 of the tracheal tube 12, such that thelight does not first pass through an optical fiber 18 before beingemitted or detected. In such an embodiment, any distance between thelight source 24 and detector 26 may be accounted for by measuringintensity profile of the returned light.

FIG. 3 is a process flow diagram illustrating a method in accordancewith some embodiments. The method is generally indicated by referencenumber 64 and includes various steps or actions represented by blocks.It should be noted that the method 64 may be performed as an automatedprocedure by a system, such as system 10. Further, certain steps orportions of the method may be performed by separate devices. Forexample, a first portion of the method 64 may be performed by a lightsource 24 and light detector 26, while a second portion of the method 64may be performed by a monitor 30. In certain embodiments, the method 64may be performed continuously or intermittently for long-term patientmonitoring or at any appropriate interval depending on the particularsituation of the intubated patient. Further, the steps of method 64 maybe performed during insertion of the tracheal tube 12 into the patient.

According to an embodiment, the method 64 begins with emitting light, atstep 66 from a light source 24, which in embodiments may be coupled toone or more optical fibers 18. The emitted light beam 46 is transmittedthrough fiber 18, which is associated with tube 12 that is inserted intoa patient's airway. The portion of the emitted light is split at step 68into an intensity reference light beam 52. The rest of the beam 46 mayexit the distal end 27 of the tube 12 before interacting with anatomicalstructures in the patient. The returned light beam 48 that is returnedthrough optical fiber 18 and received by the detector 26 at step 70 maycarry information about the relative position of the tube 12 and theanatomical structure that is carried in the sample signal, generated atstep 72. The intensity of the returned light beam 48, I_(r), at thedetector 26, may be used to calculate a placement parameter. At step 74,the intensity reference beam is detected by the detector 26 to generatethe intensity reference signal, I_(o), at step 76.

A monitor 30 may perform analysis of the sample signal and the referencesignal at step 78. In embodiments, the monitor may amplify and/or filterone or both of the sample signal and the reference signal prior to theanalysis. A monitor 30 may determine a placement parameter at step 80 todetermine if this the distance, d, 44 between the distal end 27 and thecarina 28 associated with a desirable placement of the tracheal tube 12.In one embodiment, the analysis may include determining the distance, d,44, or R 45, between the distal end 27 to the carina 28, which inembodiments may be determined by the following equation:R=1/2(RI _(o) /I _(r))^(1/2),where R a function of optical properties of the carina surface, I_(o) isthe optical intensity of the light beam 46 at the fiber end, and I_(r)is the received intensity of the returned light beam 48. In oneembodiment, R 45 may be the placement parameter. In certain embodiments,a placement parameter may be a ratio of a calculated distance and anempirically derived or clinically measured distance associated withproper tube placement. It should be appreciated that there may beseveral empirically derived distances, depending on the size, age, orsex of the patient. A placement parameter may also be an average or meanof multiple data points or measurements. A placement parameter may alsoinclude a graphical, visual, or audio representation of thetube/anatomical structure distance. For example, a placement parameterassociated with proper placement may include green light indicated on adisplay or a short tone generated by a speaker associated with monitor30. Similarly, a placement parameter associated with improper placementof the tube 12 may trigger an alarm at step 82, which may include one ormore of an audio or visual alarm indication. In one embodiment, thealarm may be triggered if the placement parameter is substantiallygreater than a predetermined value, substantially less than apredetermined value, or outside of a predetermined range. For example,proper tube placement may involve comparing a measured distance R 45 ofthe distal end 27 to carina 28 to a predetermined range of 1-5 cm. In anembodiment, the predetermined target distance may differ for adult men,who may have, in an embodiment, a target distance of 3-4 cm, and adultwomen, for whom the target distance may be 2-3 cm. In other embodiments,the alarm may be triggered if the measured distance R is less than 3 cm,less than 2 cm, or less than 1 cm.

FIG. 4 is a perspective view of an exemplary tracheal tube 12 accordingto certain embodiments. As shown, the tube 12 may include a cuff 14 thatmay be inflated via inflation lumen 84. The tracheal tube 12 may alsoinclude a suction lumen 86 for aspirating secretions that may form abovethe cuff 14. The tracheal tube 12 may also include a plurality of fiberbundles 88. Each fiber bundle may include one or more optical fibers 18.In embodiments, the transmitting and detecting may also take placewithin a single fiber. As shown, the fiber bundles 88 may extend throughthe walls 90 of the tracheal tube 12 such that they are substantially inline with a flow path 92 of the tracheal tube 12. The fibers bundles 88may include any appropriate optical connector 94 for connecting thefiber bundles 88 to downstream components of the system 10, such as thebean splitter 50 or the light source 24 or light detector 26.

The tube 12 and the cuff 14 may be formed from materials having suitablemechanical properties (such as puncture resistance, pin hole resistance,tensile strength), chemical properties (such as biocompatibility). Inone embodiment, the walls of the cuff 14 are made of a polyurethanehaving suitable mechanical and chemical properties. An example of asuitable polyurethane is Dow Pellethane® 2363-80A. In anotherembodiment, the walls of the cuff 14 are made of a suitable polyvinylchloride (PVC). In certain embodiments, the cuff 14 may be generallysized and shaped as a high volume, low pressure cuff that may bedesigned to be inflated to pressures between about 15 cm H₂O and 30 cmH₂O. The system 10 may also include a respiratory circuit (not shown)connected to the endotracheal tube 12 that allows one-way flow ofexpired gases away from the patient and one-way flow of inspired gasestowards the patient. The respiratory circuit, including the tube 12, mayinclude standard medical tubing made from suitable materials such aspolyurethane, polyvinyl chloride (PVC), polyethylene teraphthalate(PETP), low-density polyethylene (LDPE), polypropylene, silicone,neoprene, polytetrafluoroethylene (PTFE), or polyisoprene.

FIG. 5 is a side view of the distal end 27 of the tracheal tube 12. Asshown, the fiber bundles 88 may extend through the walls 90 of thetracheal tube. In certain embodiments, the fiber bundles 88 may beembedded or coextruded within an extruded tracheal tube 12. When thetube 12 is manufactured, the distal end 27 may be cut on a slant tofacilitate insertion of the tube 12 in the trachea. After the tube iscut, the fiber bundles 88 may be terminated by any suitable technique.

The fiber bundles 88, or, in some embodiments, individual fibers, may bedistributed around the circumference 96 of the tube wall 90. In anembodiment, three optical bundles may be substantially evenly spacedabout the circumference 96.

As shown the positioning of the fiber bundles 88 or single fibers mayinfluence the path of the light from the distal end 27 of the tube 12 tothe anatomical structure. Arrows 98, 100, and 102 illustrate threedifferent light paths from bundles 88 a, 88 b, and 88 c, respectively,to anatomical structures at or proximate to the carina 28. Arrow 98 hasa somewhat shorter path than arrow 100, which is related to its positionaround the circumference 96 relative to the carina 28, as well asdifferences in the topography of the carina 28. In addition, slightchanges in the angle within the trachea of the distal end 27 of the tube12 may influence the path of light to and from the fiber bundles 88. Incertain embodiments, light detected from all three fiber bundles 88 maybe combined or averaged to generate the data used to determine aplacement parameter. In addition, the differences in path length betweenmultiple bundles may be used to determine a placement parameter that isindicative of the orientation of the distal end 27 within the trachea.Changes in this orientation (e.g., angular displacement) may indicate ashift in tube placement that may influence cuff pressure and sealing.

In certain embodiments, the fibers or fiber bundles 88 may be formedfrom materials such as quartz, glass, or a transparent plastic, such aspoly(methyl methacrylate) or polystyrene with a fluoropolymer cladding.Examples of optical fibers include single-mode fibers, multi-modefibers, photonic-crystal fibers, hollow-core fibers,polarization-maintaining fibers and dual-clad fibers. Typical diametersfor optical fibers are from 5 to 1,000 micrometers. The optical fibermay be a single-mode fiber or a multi-mode fiber.

While the disclosure may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the embodiments provided hereinare not intended to be limited to the particular forms disclosed.Indeed, the disclosed embodiments may not only be applied tomeasurements of tracheal tube placement relative to anatomicalstructures in the tracheal, but these techniques may also be utilizedfor the measurement and/or analysis of the placement of other suitablemedical devices relative to other anatomical structures. For example,the present techniques may be utilized for the measurement and/oranalysis of tracheal tubes relative to tracheal walls or the vocalcords. In addition, the present techniques may be employed indetermining appropriate placement of any medical device, such as astent, catheter, implant, feeding tube, cardiac device, drug deliverydevice, or pump. Rather, the various embodiments may cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the disclosure as defined by the following appended claims.

What is claimed is:
 1. A medical device for determining placement of atracheal tube in a subject comprising: a processor configured to executeinstructions for: driving a light source to emit light through aplurality of optical conductors circumferentially spaced apart on abeveled distal end of a tracheal tube disposed in a subject, wherein thebeveled distal end is slanted relative to a gas flow pathway of thetracheal tube; determining an intensity of the emitted light from eachof the respective plurality of optical conductors; receiving informationfrom a first detector configured to receive returned light emitted fromeach of the respective plurality of optical conductors after interactionwith an anatomical structure of the subject; determining an intensity ofthe returned light emitted from each of the respective plurality ofoptical conductors based at least in part upon the information from thefirst detector; and determining a relative position of the beveleddistal end of the tracheal tube within a trachea of the subject relativeto the anatomical structure based at least in part on the intensity ofthe emitted light from each of the respective plurality of opticalconductors and the intensity of the returned light emitted from each ofthe respective plurality of optical conductors and a difference in pathlength between the plurality of optical conductors wherein thedifference in path length is representative of a position of eachrespective optical conductor about the beveled distal end; and a memorystoring the instructions; wherein the processor is configured to accessthe memory to execute the instructions.
 2. The device of claim 1,wherein the processor is configured to determine the relative positionbased upon an algorithm that implements an equation generally of theform:R=1/2(RI _(o) /I _(r))^(1/2), where R is a placement parameter, R is afunction of optical properties of the anatomical structure, I_(o) is theintensity of the emitted light, and I_(r) is the intensity of thereturned light.
 3. The device of claim 1, comprising a displayconfigured to display an indication of the relative position of thebeveled distal end of the tracheal tube.
 4. The device of claim 1,wherein the device comprises a light drive coupled to the processor, andwherein the processor is configured to execute instructions for causingthe light drive to drive the light source to emit the light through eachof the plurality of optical conductors.
 5. The device of claim 1,comprising the light source configured to emit the light through theplurality of optical conductors.
 6. The device of claim 1, wherein theprocessor is configured to execute instructions for receivinginformation from a second detector configured to receive the emittedlight from each of the respective plurality of optical conductors, andwherein the processor is configured to execute instructions fordetermining the intensity of the emitted light for each of therespective plurality of optical conductors based at least in part uponthe information from the second detector.
 7. The device of claim 1,wherein the intensity of the emitted light is stored in the memory. 8.The device of claim 1, comprising the plurality of optical conductors,wherein each of the plurality of optical conductors comprises an opticalfiber bundle comprising at least one emitting fiber and at least onereturn fiber.
 9. A system for determining placement of a tracheal tubein a subject comprising: a tracheal tube comprising a plurality ofoptical conductors circumferentially spaced apart on a beveled distalend of the tracheal tube, wherein the beveled distal end is slantedrelative to a gas flow pathway of the tracheal tube; a light sourceconfigured to emit light through each of the respective plurality ofoptical conductors when the tracheal tube is disposed in the subject; afirst photodetector configured to receive returned light emitted fromeach of the respective plurality of optical conductors and to determinean intensity of the returned light from each of the respective pluralityof optical conductors; and a processor configured to determine arelative position of the beveled distal end of the tracheal tube withina trachea of a subject relative to an anatomical structure based atleast in part on the intensity of a reference light and the returnedlight from each of the respective plurality of optical conductors and adifference in path length between the plurality of optical conductorswherein the difference in path length is representative of a position ofeach respective optical conductor about the distal end.
 10. The systemof claim 9, wherein the reference light comprises light emitted from thelight source.
 11. The system of claim 9, comprising a secondphotodetector configured to receive the emitted light and to determinethe intensity of the reference light based at least in part on theemitted light.
 12. The system of claim 9, wherein the intensity of thereference light is stored in a memory.
 13. The system of claim 9,wherein the intensity of the reference light is stored in an encoderassociated with the light source.
 14. A system for determining placementof a tracheal tube in a subject comprising: a tracheal tube comprising aplurality of optical conductors circumferentially spaced apart on abeveled distal end of the tracheal tube, wherein the beveled distal endis slanted relative to a gas flow pathway of the tracheal tube; a lightsource configured to emit light through each of the respective pluralityof optical conductors when the tracheal tube is disposed in the subject;a photodetector configured to receive returned light emitted from eachof the respective plurality of optical conductors and to determine anintensity of the returned light from each of the respective plurality ofoptical conductors; a processor configured to: determine a relativeposition of the beveled distal end of the tracheal tube within a tracheaof a patient relative to an anatomical structure based at least in parton the intensity of the returned light from each of the respectiveplurality of optical conductors and a difference in path length betweenthe plurality of optical conductors wherein the difference in pathlength is representative of a position of each respective opticalconductor about the distal end; and determine a placement parameter ofthe tracheal tube based on a difference in intensity between emittedlight and returned light for at least one of the plurality of opticalconductors, wherein the placement parameter is a distance between therelative position of the beveled distal end of the tracheal tube and theanatomical structure.
 15. The system of claim 14, comprising a displayconfigured to display an indication of the relative position of thebeveled distal end of the tracheal tube.
 16. The system of claim 14,comprising a display configured to display an indication of theplacement parameter.
 17. The system of claim 14, wherein the processoris configured to provide instructions to trigger an alarm if theplacement parameter is indicative of improper placement of the trachealtube.